In a pneumatic tire, it is known that a helical cord (curled cord) shaped in the helical state (circular spring state) and curled so as to form a circular shape when seen from the longitudinal direction, for example, is used as a stretchable and elastic internal reinforcing member. Also, in the past, as a manufacturing apparatus of such a cord, an apparatus that manufactures a helical cord without ply by applying circular shaping while collecting and driving a large number of steel wires has been known (See Patent Document 1).
However, in the case of a circular helical cord having the constant length-to-width ratio of the shaping form, since characteristics including stretching properties, rigidity and the like depend on a shaping diameter (outer diameter dimension of the circular shape) of the cord and stretching properties, an arrangement dimension and the like are determined by a relationship with a shaping diameter, there is a problem that they cannot be selected freely but are restricted in practical use. Specifically, when this helical cord is applied to a tire constituent member such that a plurality of the cords is coated with unvulcanized rubber so as to form a sheet-shaped reinforcing body, if the shaping diameter needs to be increased in order to obtain required stretching properties, the thickness of the reinforcing body itself is also increased accordingly. Thus, an application range might be narrowed such that the reinforcing body cannot be used due to the relationship with an installation space in a tire or can be used only for a limited application. As described above, the circular helical cord has a low degree of freedom in application and its application tends to be limited.
On the other hand, as a similar reinforcing member for a tire, a high elongation (H.E.) cord and a wavy cord shaped in the wavy form in the longitudinal direction have been used. However, with the high elongation cord, there is a possibility that a sufficient elongation rate cannot be obtained and large deformation applied during manufacture or use of the tire cannot be handled, which limits an application range. On the other hand, since the deformation directions of the wavy cord lie in the same plane, the shape and rigidity of the cord are different in directions and the characteristics of the cord come to have directivity, which limits a portion where the cord is to be used or an attitude of the cord.